<?php
/**
 * Slipstream :: Highly adaptive dependency injection framework
 * Copyright 2010-2011 Ian Unruh (Xerof3ar)
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace Slipstream\Configuration\Context;

use ArrayIterator;
use ArrayObject;
use Slipstream\Infrastructure\Context\Relevance\WeightComparator;
use Slipstream\Configuration\ContextInterface;

/**
 * Walker that uses a relevance comparator to sort contexts based on
 * how relevance they are to the target context
 * 
 * @author Ian Unruh (Xerof3ar) <ianunruh@gmail.com>
 * @since Class avaliable since release 1.0
 */
class SortedWalker extends BaseWalker
{
	/**
	 * @var WeightComparator
	 */
	protected $comparator;
	
	/**
	 * Class constructor
	 * 
	 * @param WeightComparator $comparator
	 * @return void
	 */
	public function __construct(WeightComparator $comparator)
	{
		$this->comparator = $comparator;
	}
	
	/**
	 * Sets the target context to walk to
	 * 
	 * @param ContextInterface $targetContext
	 * @return void
	 */
	public function setTargetContext(ContextInterface $targetContext)
	{
		parent::setTargetContext($targetContext);
		$this->comparator->setTargetContext($targetContext);
	}
	
	/**
	 * Creates an iterator for the current depth of the walker
	 * 
	 * @param ArrayObject<ContextInterface>
	 * @return Iterator<ContextInterface>
	 */
	protected function createCurrentIterator(ArrayObject $contexts)
	{
		$contexts = array_values($contexts->getArrayCopy());
		usort($contexts, array($this->comparator, 'compare'));
		return new ArrayIterator($contexts);
	}
}